Lubrication system for waste heat recovery gear box

ABSTRACT

A lubrication system and method for an engine arc provided. In some embodiments, the lubrication method comprises driving a lube pump with a gearbox in a power drive housing, the gearbox including an expander shaft of an expander of a waste heat recovery system; suctioning lubrication fluid, with the lube pump, from a lube sump in the power drive housing; lubricating, with the lubrication fluid, an expander shall bearing supporting the expander; and after lubricating the expander shall bearing, transferring the lubrication fluid to the lube sump waste heat recovery power drive and lubrication system therefor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Pat. No. 9,932,889, issuedApr. 3, 2018, which is a § 371 application of International ApplicationNo. PCT/US2016/055087, filed Oct. 2, 2016, which claims the benefit ofcommonly-owned U.S. Patent Application No. 62/236,127, filed Oct. 1,2015 and U.S. Patent Application No. 62/294,058, filed Feb. 11, 2016;the disclosures of said applications are incorporated herein in theirentirety by reference thereto.

FIELD OF THE DISCLOSURE

The disclosure generally relates to waste heat recovery systems forinternal combustion engines and to waste heat recovery systemlubrication systems and methods.

BACKGROUND OF THE DISCLOSURE

Internal combustion engines generate heat during the combustion process.About half of the energy generated by the combustion process may bedelivered to the flywheel of the engine. The discharged heat energy thatis not used to perform useful work is typically known as “waste heat.”Waste heat recovery (“WHR”) systems aim to capture some of the wasteheat energy by recovering heat energy and using it to drive an expanderto convert the recovered heat energy to power, thereby potentiallyincreasing the combustion efficiency. Example expanders include turbinesand pistons.

Some WHR systems utilize a Rankine cycle (“RC”). The RC is athermodynamic process in which heat is transferred to a working fluid inan RC circuit. The working fluid is pumped to a boiler where it isvaporized. The vapor is passed through an expander and then through acondenser, where the vapor is condensed back to a liquid. The expandingworking fluid vapor causes the expander to rotate, thereby convertingthe waste heat energy to mechanical energy. The mechanical energy may betransmitted to engine system components, such as a pump, a compressor, agenerator, etc.

WHR systems are complex, require fluid circuits, and include manycomponents that add weight to any vehicle powered by the internalcombustion engine. Accordingly, it is desirable to provide an improvedWHR system that is more compact and less complex than present WHRsystems.

The background of the disclosure is described herein to explain thecontext of the present invention. This is not to be taken as anadmission or a suggestion that any of the material referred to waspublished, known or part of the common general knowledge in the art towhich the present invention pertains, in the United States or in anyother country, as at the priority date of any of the claims.

SUMMARY OF DISCLOSED EMBODIMENTS

A waste heat recovery power drive system for an internal combustionengine, a waste heat recovery system, and lubrication systems andmethods for waste heat recovery power drive systems are provided. Thewaste heat recovery power drive system includes a waste heat recoverysystem and a gearbox structured to transfer power from the wast heatrecover system to the crankshaft of the engine. In some embodiments, thegearbox mechanically couples a lube pump and a feed pump of the wasteheat recovery system on a common shaft driven by an expander of thewaste heat recovery system, providing a compact integrated cooling,lubrication, and power transfer system. In some embodiments, a unitaryassembly includes the gearbox and the expander and is removable from theengine as a unit.

In some embodiments, the lubrication method comprises driving a lubepump with a gearbox in a power drive housing, the gearbox including anexpander shaft of an expander of a waste heat recovery system;suctioning lubrication fluid, with the lube pump, from a lube sump inthe power drive housing; lubricating, with the lubrication fluid, anexpander shaft bearing supporting the expander; and after lubricatingthe expander shaft bearing, transferring the lubrication fluid to thelube sump.

In some embodiments, a combustion engine comprises a crankshaft; a wasteheat recovery system including an expander having an expander shaft; alube pump; an output shaft coupled to the lube pump; a firstspeed-reducing means for transferring power from the expander shaft tothe output shaft to drive the lube pump; and a second speed-reducingmeans for transferring power from the output shaft to the crankshaft.

In some embodiments, a lubrication system comprises a power drivehousing including an enclosure cover mounted on a power drive housingbody; a lube sump enclosed by the power drive housing; a first geartrain adapted to be driven by an expanding device of a waste heatrecovery system having an expander shaft; an output shaft supporting thelube pump and driven by the first gear train; and a lube sump, whereinthe lube pump is configured to suction a lubrication fluid from the lubesump to lubricate the first gear train.

In a further embodiment, a waste heat recovery power drive system isprovided, comprising a waste heat recovery system comprising a boileroperatively coupled to an engine so as to receive heat energy from theengine and transfer the heat energy to a working fluid; and an expanderfluidly coupled to the boiler so as to receive the working fluid fromthe boiler, the expander structured to convert heat energy from theworking fluid to mechanical energy; a gearbox operatively coupled to theexpander; a front engine accessory drive comprising a belt driveoperatively coupling the gearbox to a crankshaft of the engine so as totransfer the mechanical energy from the gearbox to the crankshaft of theengine; and a unitary assembly comprising the front engine accessorydrive, the gearbox, and the expander, the unitary assembly beingremovable from the engine as a unit.

There has thus been outlined, rather broadly, various features of theinvention so that the present contribution to the art may be betterappreciated. The attendant advantages of this invention, the manner ofattaining them, and other features of the present invention, will becomemore apparent and will be better understood by reference to thefollowing detailed description of disclosed embodiments taken inconjunction with the accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an embodiment of an engine system,including an engine and a WHR power drive system.

FIG. 2 is a perspective view illustration of an embodiment of an enginesystem, including an engine and a WHR power drive system.

FIG. 3 is a front elevational view illustration of a gearbox of the WHRpower drive system of FIG. 2.

FIG. 4 is a front elevational view illustration of the gearbox of FIG.3, with an enclosure cover omitted.

FIG. 5 is a side elevational view illustration of a hub of the gearboxof FIG. 3.

FIG. 6 is a perspective view illustration of a bull gear of the gearboxof FIG. 3.

FIG. 7 is a front elevational view illustration of the gearbox of FIG.3.

FIG. 8 is a cross-sectional side view illustration of the gearbox ofFIG. 3.

FIG. 9 is a front elevational view illustration of the gearbox of FIG. 3showing a flow control valve of the WHR power drive system of FIG. 2.

FIG. 10 is a front elevational view illustration of the gearbox of FIG.3 showing a bypass valve of the WHR power drive system of FIG. 2.

FIG. 11 is a front elevational view illustration of the gearbox of FIG.3 showing an expander of the WHR power drive system of FIG. 2.

FIG. 12 is a perspective view illustration of the WHR power drive systemof FIG. 2.

FIG. 13 is a partial cross-sectional view illustration of the WHR powerdrive system of FIG. 2.

FIG. 14 is a schematic diagram of an embodiment of a gearbox of a WHRpower drive system.

FIG. 15 is a flow diagram of an embodiment of a lubrication circuit ofthe WHR power drive system of FIG. 14.

FIG. 16 is a partially sectioned perspective view illustration of agearbox according with the invention and set forth in the disclosure,sectioned in part along planes A-A, B-B, and C-C.

FIG. 17 is a perspective view illustration of the gearbox of FIG. 16,

FIG. 18 is a perspective view illustration of the gearbox of FIG. 16sectioned along plane A-A.

FIG. 19 is a perspective view illustration of the gearbox of FIG. 16with an enclosure cover removed.

FIG. 20 is a perspective view illustration of the gearbox of FIG. 16sectioned along plane B-B.

FIG. 21 is a perspective view illustration of the gearbox of FIG. 16sectioned along plane C-C.

FIG. 22 is a partially sectioned perspective view illustration of thegearbox of FIG. 16.

FIGS. 23 and 24 are plan and exploded perspective view illustrations ofcomponents of a lubrication circuit.

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the drawings representembodiments of various features and components according to the presentinvention, the drawings are not necessarily to scale and certainfeatures may be exaggerated in order to better illustrate and explainthe present invention.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings, which are described below. The embodiments disclosed beloware not intended to be exhaustive or limit the invention to the preciseform disclosed in the following detailed description. Rather, theembodiments are chosen and described so that others skilled in the artmay utilize their teachings. It will be understood that no limitation ofthe scope of the invention is thereby intended. The invention includesany alterations and further modifications in the illustrated devices anddescribed methods and further applications of the principles of theinvention which would normally occur to one skilled in the art to whichthe invention relates.

Except where a contrary intent is expressly stated, the following termshave the following meanings:

“About” as used herein when referring to a measurable value such as anamount, a temporal duration, and the like, is meant to encompass theexact numerical value as though it had been recited without the term“about”.

The transitional terms “comprises,” “comprising,” “containing,” and“having” and the like mean “includes,” “including,” and the like, areinclusive or open ended terms and do not exclude additional, unspecifiedelements or method steps. By contrast, the transitional term“consisting” is a closed term which does not permit addition ofunspecified terms.

“Example” as used herein is intended to indicate possible examples,representations, and/or illustrations of elements or embodiments andsuch term is not intended to connote that such elements or embodimentsare necessarily extraordinary or superlative examples.

The terms “first,” “second,” “third,” “fourth,” and the like in thedescription and in the claims, if any, are used for distinguishingbetween similar elements and not necessarily for describing a particularsequential or chronological order. It is to be understood that any termsso used are interchangeable under appropriate circumstances such thatthe embodiments described herein are, for example, capable of operationin sequences other than those illustrated or otherwise described herein.Similarly, if a method is described herein as comprising a series ofsteps, the order of such steps as presented herein is not necessarilythe only order in which such steps may be performed, and certain of thestated steps may possibly be omitted and/or certain other steps notdescribed herein may possibly be added to the method.

Except where a contrary intent is expressly stated, terms are used intheir singular form for clarity and are intended to include their pluralform.

Actions recited in the claims may be performed in any order, and inparticular an order different than the order presented, unless an orderis expressly or inherently claimed. The depictions in the accompanyingfigures do not necessarily require a particular order or sequentialorder.

Occurrences of the phrase “in one embodiment,” or “in one aspect,”herein do not necessarily all refer to the same embodiment or aspect.

Referring generally to the figures, various embodiments relate to WHRpower drive systems. According to various embodiments, WHR power drivesystems may include several components or subsystems structured tooptimize the amount of power recovered from waste heat of an engine.Multiple ones of the components or subsystems may be integrated into asingle unitary assembly. The recovered power may be utilized in severalways, such as to supplement power to the crankshaft of the engine, topower accessories, to generate electrical energy, etc.

In an embodiment, a WHR power drive system includes a WHR system, agearbox, and a front engine accessory drive (“FEAD”) In one example ofthis embodiment, an expander, a feed pump, and control valves of the WHRsystem, along with a gear train of the gearbox and the FEAD, areintegrated into a single unitary assembly.

In some embodiments, a gearbox is structured to transfer energy from theWHR system to the crankshaft of the engine. In one variation, thegearbox comprises a combination of hard gearing and a flexible dampingbelt drive so as to maximize operational efficiency of the WHR powerdrive system and reduce vibration of the WHR power drive system.

In some embodiments, the gearbox defines a cooling passage that isfluidly coupled to a working fluid circuit and structured to receive aworking fluid from the working fluid circuit so as to cool the gearboxand oil disposed therein.

In some embodiments, an expander used for converting energy in an RC maybe positioned so as to facilitate oil drainage from the WHR power drivesystem.

In some embodiments, a FEAD includes auxiliary engine systems andcomponents that are driven by energy converted by the WHR system.

The WHR power drive system may be structured such that the entire systemmay easily be removed, and thus, by replacing the entire WHR power drivesystem, on-site repair and the associated downtime may be avoided. Inaddition, a size and a weight of the WHR power drive system may beminimized by the structure described in the present disclosure, therebyreducing material costs, improving efficiency (e.g., fuel economy), andenabling the system to be implemented in smaller spaces.

FIG. 1 is a block diagram of an embodiment of an engine system, denotedby numeral 100, including an engine 102 and a WHR power drive system104. Engine 102 may be an internal combustion engine, such as acompression ignition or spark ignition engine, and may be fueled byvarious types of fuels, such as diesel, gasoline, compressed naturalgas, ethanol, etc. The WHR power drive system 104 includes a WHR system106, a gearbox 108, and a FEAD 110. In general, WHR system 106 isstructured to convert waste heat produced by engine 102 into usefulenergy, such as mechanical energy (e.g., which may be transferred to thecrankshaft of engine 102 or used to power components of FEAD 110) and/orelectrical energy (e.g., which may be stored in a battery for lateruse). WHR system 106 includes a working fluid circuit 122 comprising acondenser 112, a boiler 114, an expander 116, a feed pump 118, and afluid control system 120, each being fluidly coupled via working fluidpassages. Feed pump 118 is structured to pump a working fluid throughworking fluid circuit 122, and fluid control system 120 is structured tocontrol fluid flow through working fluid circuit 122.

In operation, boiler 114 operates as a heat exchanger to transfer heatenergy from waste heat produced by engine 102 to the working fluid inworking fluid circuit 122, so as to vaporize the working fluid. Thevaporized working fluid is transferred from boiler 114 to expander 116,which is positioned along working fluid circuit 122 downstream of boiler114. As the vaporized working fluid travels through expander 116, thevapor expands, thereby driving a turbine of expander 116. The vaporizedworking fluid flows from expander 116 to condenser 112, where theworking fluid is cooled and condensed back to a liquid, and subsequentlyrecycled through working fluid circuit 122. According to variousembodiments, expander 116 may be a turbine expander, magnetic couplingexpander, piston expander, or any other type of expander.

Gearbox 108 includes a first gear train 124 and a hub 126. First geartrain 124 and hub 126 may be positioned within an enclosure (not shown),which may also house various other components of WHR system 106, suchas, for example, condenser 112, feed pump 118, and fluid control system120. In addition, the enclosure may provide mounting surfaces forvarious components of FEAD 110. First gear train 124 operatively couplesexpander 116 and hub 126 so as to transfer torque from expander 116 tohub 126. First gear train 124 may include one or more gears structuredto reduce a rotational velocity of hub 126 relative to that of expander116. Hub 126 is operatively coupled to one or both of feed pump 118 ofWHR system 106, and a pulley 130 of FEAD 110. Accordingly, energyrecovered by WHR system 106 via expander 116 is utilized to drive one orboth of feed pump 118 of WHR system 106 and pulley 130 of FEAD 110. Insome embodiments, gearbox 108 may operatively couple expander 116 toengine 102 (e.g., to the crankshaft of engine 102) to transmit energy toengine 102. In one example, gearbox 108 operative couples expander 116via a direct gear-to-gear connection. In some embodiments, gearbox 108may operatively couple expander 116 to other components of engine system100, or components external to engine system 100.

FEAD 110 includes an accessory 132 operatively coupled to pulley 130 viaa belt 134. Although not shown in FIG. 1, FEAD 110 may include severalpulleys 130 and several accessories 132. In some embodiments, one ormore accessories 132 may be coupled to gearbox 108 via a directgear-to-gear connection. Accessories 132 may include, for example, analternator, a water pump, a compressor, etc. In one variation, belt 134is operatively coupled to a crankshaft 136 of engine 102. Accordingly,energy recovered by WHR system 106 may be transmitted back to engine 102via FEAD 110.

Some embodiments utilize a combination of one or more belt drives andone or more direct gear-to-gear connections to operatively couple anycombination of engine 102, WHR system 106, gearbox 108 and FEAD 110. Insome embodiments, arrangements that utilize a combination of belt drivesand geared connections may exhibit lower noise and vibration than otherarrangements.

FIG. 2 is a perspective view illustration of an engine system 200,including an engine 202 and a WHR power drive system 204, according toan embodiment. WHR power drive system 204 may be similar to WHR powerdrive system 104 of FIG. 1. As illustrated in FIG. 2, WHR power drivesystem 204 includes a WHR system 206, a gearbox 208, and an FEAD 210. Inthe embodiment illustrated in FIG. 2, WHR power drive system 204 isstructured such that some or all of the components of each of WHR system206, gearbox 208, and FEAD 210 are integrated into a single unitaryassembly that is removable from the engine 202 as a single component.Gearbox 208 is best seen in FIG. 12. WHR power drive system 204 includesan enclosure 228 that is shared by both WHR system 206 (not shown) andgearbox 208. Enclosure 228 is structured to enclose and protect variouscomponents of WHR system 206 and gearbox 208.

FIGS. 3 and 4 are front elevational view illustrations of gearbox 208 ofWHR power drive system 204. Enclosure 228 includes an enclosure cover238, shown in FIG. 3, which is removable to provide access to componentsof WHR system 206 and gearbox 208. Enclosure 228 also defines integralmounting features 240 (e.g., brackets or standoffs) for variouscomponents, including components of FEAD 210. Accordingly, enclosure 228eliminates the need for separate mounting brackets for FEAD 210. In FIG.4, enclosure cover 238 is omitted. As illustrated in FIG. 4, a hub 226and a bull gear 242 of a first gear train 224 of gearbox 208 aredisposed within enclosure 228. Bull gear 242 is operatively coupled tohub 226 such that bull gear 242 does not rotate relative to hub 226. Invarious embodiments, bull gear 242 is press-fit or keyed to hub 226.Bull gear 242 is further operatively coupled (e.g., in meshedengagement) with a pinion 244 of an expander 216 of WHR system 206.Accordingly, bull gear 242 is structured to transmit torque fromexpander 216 of WHR system 206 to hub 226.

FIG. 5 is a side elevational view illustration of hub 226 of gearbox208. Hub 226 supports bull gear 242 and is structured to transmit torquefrom WHR system 206 to a pulley (not shown) of FEAD 210. Hub 226 extendsalong a longitudinal axis 246 from a first end 248 to a second end 250.Hub 226 defines a recess 251 proximate first end 248. Recess 251 isstructured to receive at least a portion of a feed pump (not shown) ofgearbox 208. Hub 226 further defines a female spline 252 (e.g., of anSAE spline coupling) extending further into hub 226 from recess 251towards second end 250. Female spline 252 is structured to receive acorresponding male spline of the feed pump. Hub 226 also includes ashaft 254 that extends along longitudinal axis 246 to second end 250.Shaft 254 defines several engagement features 256 structured to engagecorresponding features of other components that are driven by hub 226.For example, hub 226 may be further structured to drive a lube pump(shown in FIG. 18) of gearbox 208, as well as a pulley (not shown) ofFEAD 210.

FIG. 6 is a perspective view illustration of bull gear 242 of gearbox208 of FIG. 3. Bull gear 242 defines a central axis 258 that, inoperation, is coaxial with the longitudinal axis 246 of hub 226. Bullgear 242 defines gear teeth 260 positioned about an outer peripheralsurface of bull gear 242. Gear teeth 260, along with gear teeth ofpinion 244 of expander 216, define a gear ratio between bull gear 242and pinion 244. In one embodiment, the gear ratio is greater than 10:1.In one embodiment, the gear ratio is 10.5:1.

FIG. 7 is a front elevational view illustration of gearbox 208 of FIG.3, with hub 226 and bull gear 242 removed from gearbox 208. Asillustrated in FIG. 7, a feed pump 218 of WHR system 206 is alsodisposed within enclosure 228, adjacent (e.g., behind in the orientationshown) hub 226 (not shown). Feed pump 218 is structured to circulate aworking fluid (e.g., a refrigerant) through a working fluid circuit.Enclosure 228 defines an intake port 262 of the working fluid circuit.

FIG. 8 is a cross-sectional side view illustration of gearbox 208 ofFIG. 3. Feed pump 218 includes a shaft 264 extending along alongitudinal axis 266 of feed pump 218. Longitudinal axis 266 of feedpump 218 is coaxial with longitudinal axis 246 of hub 226 (illustratedin FIG. 5) when assembled. Shaft 264 defines a male spline 268structured to engage female spline 252 of hub 226. Enclosure 228 definesa suction cavity 270 and a discharge cavity 272, which form a portion ofthe working fluid circuit. Feed pump 218 is structured to draw workingfluid from suction cavity 270 and to discharge the working fluid intothe discharge cavity 272. A bearing 269 supports feed pump 218 and shaft264.

FIG. 9 is a front elevational view illustration of gearbox 208 showing aflow control valve 274 of WHR system 206 of FIG. 2. Flow control valve274 is part of a fluid control system of WHR system 206. Flow controlvalve 274 is removably coupled to enclosure 228 of gearbox 208. Flowcontrol valve 274 controls flow of the working fluid through the workingfluid circuit. In particular, flow control valve 274 controls flow ofthe working fluid to a boiler (not shown) of WHR system 206. In someembodiments, flow control valve 274 also controls flow of the workingfluid from the working fluid circuit to other fluid circuits, such anexhaust gas recirculation (“EGR”) fluid circuit.

FIG. 10 is a front elevational view illustration of gearbox 208 showinga bypass valve 276 of WHR system 206 of FIG. 2. Bypass valve 276 is alsopart of the fluid control system of WHR system 206. Bypass valve 276 isremovably coupled to enclosure 228 of gearbox 208. Bypass valve 276controls flow of the working fluid through the working fluid circuit byselectively bypassing flow of the working fluid to an inlet of feed pump218 so as to bypass the boiler (not shown).

FIG. 11 is a front elevational view illustration of gearbox 208 of FIG.3 showing expander 216 of WHR system 206 of FIG. 2. Expander 216includes an oil drain 280 positioned on a lower surface 281 of gearbox208 to facilitate oil drainage from the system. In particular, oil drain280 is positioned on a surface that is riot obstructed by othercomponents, such that an operator may access oil drain 280.

FIG. 12 is a perspective view illustration of WHR power drive system 204of FIG. 2. FEAD 210 includes one or more accessories of the enginesystem 200, as well as driving components structured to transmit powerto drive the accessories. For example, the driving components mayinclude belt drives, pulleys, direct gearing, and clutches. According toan embodiment, FEAD 210 is structured to transmit power from WHR system206 to the accessories of FEAD 210. In some embodiments, one or moreaccessories may be powered in other ways, such as by electrical orhydraulic power. FEAD 210 includes a first accessory 232, a secondaccessory 284, and a third accessory 285. Example accessories include acompressor, a water pump, and an alternator or motor-generator unit. Thefirst and second accessories 232, 284 are powered by a belt drivesystem, including a belt 234. First and second accessories 232, 284 areoperatively coupled to belt 234 via respective first and second pulleys286, 287. FEAD 210 also includes a clutch 282 structured to selectivelycouple first and second accessories 232, 284 of FEAD 210 to WHR system206 (not shown). More specifically, clutch 282 is selectively coupled tofirst gear train 224 of gearbox 208, which operatively couples expander216 of WHR system 206 with FEAD 210. The clutch 282 includes a clutchpulley 283 structured to operatively couple clutch 282 to first andsecond pulleys 286, 287 of, respectively, first and second accessories232, 284, via the belt 234.

In one embodiment, third accessory 285 is operatively coupled to WHRsystem 206 via a second gear train (not shown) of gearbox 208. Forexample, third accessory 285 may include an input shaft with a pinionthat engages the second gear train so as to transfer torque from WHRsystem 206 to third accessory 285. In other embodiments, third accessory285 is operatively coupled to the belt 234.

In some embodiments, second pulley 287 is a dual pulley. A second belt(not shown) operatively couples FEAD 210 with the crankshaft of engine202 (not shown). Accordingly, energy may be transferred from thecrankshaft of the engine to FEAD 210 via the second belt. In oneembodiment, third accessory 285 is a motor-generator unit, which mayoperate to power the components of FEAD 210 when engine 202 is notrunning. The belts and pulleys may comprise a belt drive.

FIG. 13 is a partial cross-sectional view illustration of WHR powerdrive system 204. The cross-section extends through several componentsof WHR power drive system 204, including feed pump 218 and expander 216of WHR system 206; first gear train 224, hub 226, enclosure cover 238,and bull gear 242 of gearbox 208; and the clutch 282 of FEAD 210. FIG.13 further illustrates a lube pump 288 of gearbox 208. Lube pump 288 isoperatively coupled to hub 226 of gearbox 208. Lube pump 288 isstructured to pump a lubricant (e.g., oil) through gearbox 208. In oneembodiment, lube pump 288 is a gerotor. In some embodiments, lube pump288 is structured to pump a lubricant through a bearing of expander 216.Accordingly, hub 226 provides integrated operation of each of feed pump218, first gear train 224, and lube pump 288.

Having described a WHR power drive system, attention is now turned tothe lubrication system for the WHR power drive. Referring to FIG. 14, aschematic representation of a gearbox 300 is provided. Gearbox 300mechanically couples a crankshaft 312 of a combustion engine to anexpander shaft 310 of an expander of the WHR system to thereby transfertorque generated by the expander to crankshaft 312. In the presentembodiment, gearbox 300 includes first and second gear trains 314, 316.First gear train 314 comprises pinion 244 mounted on expander shaft 310and bull gear 242 mounted on an output shaft 352. In one variation,output shaft 352 is coupled to, and rotates with, hub 126, thereforeexpander shaft 310 drives output shaft 352 and thereby also drives feedpump 118 forming an integrated system. Bull gear 242 has teeth 260engaging teeth 346 of pinion 244 to drive bull gear 242 via expandershaft 310. Second gear train 316 comprises a drive pulley 320 mounted onoutput shaft 352 and a load pulley 322 connected to crankshaft 312 andcoupled to drive pulley 320 by a belt 324. Also mounted on output shaft352 is a portion of lube pump 288. Thus, expander shaft 310 drives lubepump 288 and simultaneously provides torque produced by recovered wasteheat to crankshaft 312. In other embodiments, first and second geartrains 314, 316 may comprise pulleys or different types of gears knownin the art.

FIG. 15 is a schematic representation of a fluid circuit 354 thermallycoupled with a lubrication circuit 360. The physical locations of thecomponents of these circuits are further described with reference toFIGS. 16-22. Fluid circuit 354 is provided to circulate a working fluidto cool lubrication fluid. Fluid circuit 354 comprises a working fluidinlet rifle 355, cooling well 356 (best shown in FIG. 20), a workingfluid outlet rifle 357, and a working fluid feed pump 358. Additionalcooling rifles (not shown) are also provided. An expander (not shown)and a condenser (not shown) complete fluid circuit 354. Working fluidfeed pump 358 pumps the working fluid through fluid circuit 354. Lubepump 288 is adjacent cooling well 356. Lubrication circuit 360, lubepump 288, a pressure dump valve 364, a lube filter 368, expander shaftbearing 342, a lube return slot 376 (best shown in FIG. 22, a lube sump380, and a differential pressure sensor 398 (best shown in FIG. 16).

FIGS. 16-22 provide partially and fully sectioned perspective views ofgearbox 300. Referring now to FIG. 16, lube pump 288 generates suctionto draw the lubrication fluid from lube sump 380 via a lube sump rifle382 having an inlet port 383, a cross-over rifle 384, and a lube pumpsuction rifle 386. A lube pump discharge rifle 390 fluidly couples lubepump 288 to pressure dump valve 364. A lube filter rifle 394 couplespressure dump valve 364 with lube filter 368. An expander rifle 398fluidly couples expander shaft bearing 342 with lube filter 368. Lubereturn slot 376 fluidly couples expander shaft bearing 342 with lubesump 380, completing lubrication circuit 360. In some embodiments, thelubrication fluid is miscible with the working fluid. In someembodiments, cooling fluid circuit 354 and lubrication circuit 360 arenot fluidly isolated, thus some amount of mixing of the fluids mayoccur. In the present embodiment, lubrication circuit 360 is independentfrom a lubrication system of the internal combustion engine. Byindependent it is meant that the fluid systems are driven by separatepumps and the fluids do not mix. Lube filter 368 is positioned in a lubefilter cavity 370. A pressure rifle 398 couples filter cavity 370 withpressure sensor 399.

Working fluid feed pump 358 is located in a feed pump cavity 412 (bestshown in FIG. 20). Gearbox 300 is partially enclosed by an enclosure400. As shown, at least lubrication circuit 360 and first gear train 314are located within enclosure 400. Pulleys of second gear train 316 arepositioned outside enclosure 400 to facilitate installation of the unitby removing belt 324. The working fluid flowing through fluid circuit354 extracts heat from enclosure 400, lube pump 288, and the lubricationfluid, to maintain a desired temperature in gearbox 300. In a variationof the present embodiment, working fluid feed pump 358 is not mounted ongearbox 300.

Referring to FIGS. 16 and 17, enclosure 400 comprises an enclosure body402 and an enclosure cover 404. Components of lubrication circuit 360are formed in enclosure body 402 and enclosure cover 404. Enclosure 400also encloses components of fluid circuit 354. Gearbox 300, andenclosure 400, may be supported by the internal combustion engine andmay be positioned at the front of the internal combustion engine, tomore easily couple gearbox 300 to crankshaft 312, as describedpreviously. FIG. 16 shows enclosure 400 partially sectioned along planesA-A, B-B, and C-C to illustrate integration of gearbox 300 andlubrication circuit 360 in a compact enclosure. FIG. 17 provides anon-sectioned perspective view of gearbox 300. FIG. 18 provides aperspective view of gearbox 300 sectioned along plane A-A. Plane A-Atraverses enclosure cover 404. FIG. 19 provides a perspective view ofgearbox 300 with enclosure cover 404 removed. FIG. 20 provides aperspective view of gearbox 300 sectioned along plane B-B. FIG. 21provides a perspective view of gearbox 300 sectioned along plane C-C.

Operation of gearbox 300 and lubrication subassembly 360 will now bedescribed in additional detail. When the combustion engine operates itgenerates heat that is recovered by the WHR system to cause expandershaft 310 to rotate, which rotates output shaft 352, and lube pump 288,at a speed (radial) proportional to the teeth ratio of pinion gear 244and bull gear 242. At the same time drive pulley 320 rotates load pulley322 to transfer torque (power) to crankshaft 312. The expander mayrotate at a very high speed relative to the speed of crankshaft 312.First and second drive trains 314, 316 have a speed reducing effect sothat the speed of load pulley 322 substantially matches the speedcrankshaft 312. Lube pump 288 draws the lubrication fluid from lube sump380 and discharges the lubrication fluid through pressure dump valve 364and lube filter 368 to expander shaft bearing 342 to lubricate expandershaft bearing 342. Pressure dump valve 364 regulates the pressuregenerated by lube pump 288, or first pressure, to a second, lower,pressure. In one example, the first pressure is reduced to 20 PSI.Differential pressure sensor 399 is configured to transmit a pressuresignal including a pressure value of a differential pressure between thesecond pressure and a pressure at lube sump 380. A pressure valueexceeding a pressure threshold indicates a fault in the lubricationcircuit. The lubrication fluid passes through lube return slot 376 andreturns to lube sump 380 by operation of gravity.

FIG. 17 illustrates enclosure 400 with enclosure cover 404 in place.Also shown is a temperature sensor 426 configured to send a temperaturesignal including temperature values representative of the temperature ofthe lubrication fluid or enclosure 400. A fault or warning signal may begenerated by an electronic control unit (not shown) if the temperaturevalue exceeds a temperature threshold, indicating loss of cooling. FIG.18 illustrates is a view of gearbox 300 sectioned along plane A-A, whichtraverses enclosure cover 404, to illustrate the portion of lubricationcircuit 360 located on enclosure cover 404. There, it can be seen thatlube pump 288 is positioned between enclosure cover 404 arid enclosurebody 402.

Turning now to FIG. 19, gearbox 300 is shown with enclosure cover 404removed. There, it is shown a hub comprising portions 430 and 432,similar to hub 126, from which output shaft 352 (not shown) extends.Bull gear 242 has an internal circular opening in contact with thecircumference of portion 430 and is affixed thereto as previouslydescribed. Lube filter 368 is positioned in a lube filter cavity 370that traverses the joint between enclosure cover 404 and drive enclosurebody 402. The location of feed pump cavity 412 is also shown. An outputshaft bearing 414 supports the hub as it rotates.

FIG. 20 provides a perspective view of gearbox 300 sectioned along planeB-B and illustrates the position of feed pump cavity 412. An expandersupply rifle 398 is coupled to lube filter cavity 370 to providelubrication fluid at the low pressure to expander bearing 342. Coolingwell 356 and cross-over rifle 384 is also shown. FIG. 21 provides aperspective view of gearbox 300 sectioned along plane C-C and showscross-over rifle 384 which is fluidly coupled by lube sump rifle 382 todraw lubrication fluid (oil) from inlet port 383 and lube sump 380.Lubrication fluid 400 is also shown.

FIG. 22 is a partially sectioned perspective view of gearbox 300 showinga lube supply slot 422 above expander shaft bearing 342, and lube returnslot 376 below. Lube supply slot 422 is fluidly coupled to expandersupply rifle 398 and causes the lubrication fluid to fall on expandershaft bearing 342 as it rotates. The lubrication fluid then falls intolube return slot 376 below and therethrough returns to lube sump 380. Acover plate 418 encloses lube pump 288 on the opposite side of enclosurecover 404. A couple of bearings 414, 420 are disposed on opposing sidesof the hub supporting output shaft 352.

FIGS. 23 and 24 provide detailed views of portions of lubricationcircuit 360 including lube filter 368, pressure dump valve 364, and lubepump 288.

While this disclosure has been described as having exemplary designs,the present disclosure can be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the disclosure using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this disclosure pertains and which fallwithin the limits of the appended claims.

I claim:
 1. A combustion engine comprising: a crankshaft; a waste heat recovery system including an expander having an expander shaft; a lube pump; an output shaft coupled to the lube pump; a first speed-reducing means for transferring power from the expander shaft to the output shaft to drive the lube pump; a second speed-reducing means for transferring power from the output shaft to the crankshaft; and an expander bearing supporting the expander shaft, a lube sump in a power drive housing, and a lube discharge rifle in the power drive housing, wherein the lube pump is configured to suction lubrication fluid from the lube sump and discharge the lubrication fluid through the lube discharge rifle to lubricate the expander bearing and return the lubrication fluid to the lube sump.
 2. The combustion engine of claim 1, further comprising a power drive housing including an enclosure cover mounted on a power drive housing body, wherein the first speed-reducing means is enclosed within the power drive housing.
 3. The combustion engine of claim 1, further comprising a cooling pump coupled to the output shaft, wherein the output shaft is configured to simultaneously drive the lube pump and the cooling pump.
 4. A combustion engine comprising: a crankshaft; a waste heat recovery system including an expander having an expander shaft; a lube pump; an output shaft coupled to the lube pump; a first speed-reducing means for transferring power from the expander shaft to the output shaft to drive the lube pump; a second speed-reducing means for transferring power from the output shaft to the crankshaft; a power drive housing including an enclosure cover mounted on a power drive housing body; and a lube sump enclosed by the power drive housing, wherein the lube pump is configured to suction a lubrication fluid from the lube sump to lubricate the first speed-reducing means.
 5. The combustion engine of claim 4, further comprising an expander bearing supporting the expander shaft, a lube sump in a power drive housing, and a lube discharge rifle in the power drive housing, wherein the lube pump is configured to suction lubrication fluid from the lube sump and discharge the lubrication fluid through the lube discharge rifle to lubricate the expander bearing and return the lubrication fluid to the lube sump.
 6. The combustion engine of claim 4, further comprising an expander bearing supporting the expander shaft, and a lube discharge rifle and a lube return slot in the power drive housing, wherein the lube pump is configured to discharge the lubrication fluid through the lube discharge rifle to lubricate the expander bearing.
 7. The combustion engine of claim 6, wherein the lube discharge rifle is positioned in the enclosure cover of the power drive housing.
 8. The combustion engine of claim 4, wherein the lubricating fluid flows through a lubrication circuit that is independent of a lubrication circuit of an internal combustion system driving the waste heat recovery system.
 9. A combustion engine comprising: a crankshaft; a waste heat recovery system including an expander having an expander shaft; a lube pump; an output shaft coupled to the lube pump; a first speed-reducing means for transferring power from the expander shaft to the output shaft to drive the lube pump; a second speed-reducing means for transferring power from the output shaft to the crankshaft; a cooling pump coupled to the output shaft; a lube sump; an expander bearing supporting the expander shaft; and a cooling circuit in the power drive housing, wherein the lube pump is operable to suction lubrication fluid from the lube sump and discharge the lubrication fluid to lubricate the expander bearing, and wherein the cooling pump is operable to pump a working fluid through the cooling circuit to transfer heat from a lubrication fluid to the working fluid.
 10. The combustion engine of claim 9, wherein the lubrication fluid is miscible with the working fluid.
 11. The combustion engine of claim 9, wherein the cooling pump is operable to circulate the working fluid through the power drive housing to cool the power drive housing.
 12. A combustion engine comprising: a crankshaft; a waste heat recovery system including an expander having an expander shaft; a lube pump; an output shaft coupled to the lube pump; a first gear train operable to transfer power from the expander shaft to the output shaft to drive the lube pump; and a second gear train operable to transfer power from the output shaft to the crankshaft; a power drive housing including an enclosure cover mounted on a power drive housing body, wherein the first gear train is enclosed within the power drive housing; and an expander bearing supporting the expander shaft, a lube sump in the power drive housing, and a lube discharge rifle in the power drive housing, wherein the lube pump is operable to suction lubrication fluid from the lube sump and discharge the lubrication fluid through the lube discharge rifle to lubricate the expander bearing.
 13. The combustion engine of claim 12, further comprising a cooling pump coupled to the output shaft, wherein the output shaft is configured to simultaneously drive the lube pump and the cooling pump.
 14. The combustion engine of claim 12, wherein the lube discharge rifle is positioned in the enclosure cover of the power drive housing.
 15. The combustion engine of claim 12, wherein the lubricating fluid flows through a lubrication circuit that is independent of another lubrication circuit of the combustion engine which is operable to drive the waste heat recovery system.
 16. The combustion engine of claim 12, further comprising a cooling circuit in the power drive housing, wherein the cooling pump is operable to pump a working fluid through the cooling circuit to transfer heat from a lubrication fluid to the working fluid.
 17. The combustion engine of claim 16, wherein the lubrication fluid is miscible with the working fluid.
 18. The combustion engine of claim 16, wherein the cooling pump is operable to circulate the working fluid through the power drive housing to cool the power drive housing. 